Recently, as the change in climates and ecosystems due to global warming is remarkable over time, the interest in this is increasing gradually. The interest in regulation of the greenhouse gas emissions as the main cause of the global warming is also increasing all over the world.
However, most people think that only carbon dioxide (CO2) contributes to the greenhouse gas emissions, but methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCS) as perfluorinated or perfluoro compounds, perfluorocarbons (PFCS), and sulfur hexafluoride (SF6) are also the main cause of global warming.
The proportion of the aforementioned compounds reaches 12.2% or so in comparison with the amount of carbon dioxide increasing sharply in the atmosphere, which means that the compounds are discharged in a considerably large amount to the atmosphere. The perfluoro compounds are discharged in a considerably large amount in the electronics-related fields that can be regarded as one of the leading industries of Korea, including semiconductors, displays, LEDs, photovoltaic applications, and the like. The proportion of the perflouro compound emissions reaches 4.4%.
In particular, a large amount of dust, sulfur hexafluoride (SF6) and silicon hexafluoride (SiF6) are discharged to the outside in a process in which F-ions are produced using a plasma device and react with an insulator to perform etching to form a uniform pattern on a substrate.
In addition, a CVD chamber cleaning process is a process which removes a coating layer coated with an insulator (SiO2) using a plasma etching method, In this process, NF3 gas is mainly used, and dust, NF3, F2, SiF4, and the like are discharged to the outside.
Various gases including the dust are mixed with a large amount of nitrogen and then are sucked into a dry pump to protect pumps and devices. Then, the gases are transferred to a post-treatment facility where only a gas scrubber is at present nearly installed.
Currently, various recycling systems are developed in which nitrogen is separated from other perfluoro compounds using a separation membrane allowing only nitrogen having the smallest particle to pass therethrough, and then the separated nitrogen is re-used and the perfluoro compounds are transferred to a re-treatment facility.
However, there is a high risk that the separation membrane will be damaged at high pressure. On the contrary, since there is a risk that the separation membrane will be decreased in the separation efficiency at low pressure, it is important to maintain a proper pressure. Nevertheless, in a structure in which several conduits are branched off from a conduit and then join with each via the separation membrane, different pressures are applied to respective separation membranes, causing a problem in that the separation membranes are damaged and the efficiency is degraded.